This invention relates to the field of coordinate positioning arrangements for machine operations such as drilling.
One well known type of machine with coordinate positioning is a drill press with a movable table mounted in a saddle. The table may be moved in the saddle along a lead screw for one coordinate, and the saddle moves along a lead screw for another coordinate. These units may also be used for other machine operations, such as milling. However, the movement of the table in ths saddle is limited to a few feet, and the movement of the saddle to about one foot. Thus, the machines are not suitable for handling very large material on the work table.
An elementary method of handling objects such as large steel plates is to have a person manually lay out the pattern of holes, center punch each one, and then drill with a hand drill. There are also methods using a magnetic drilling head.
There are also known arrangements for handling large plates with great accuracy (0.001 inch) which are very expensive. These include a radial drill press in which a drill head moves out on arms; and a jig boring mill with a moving table. However, there are many applications in which less accuracy is required, for example 1/64 inch may be adequate. In such situations the expensive machines cannot be justified; their accuracy is wasted. On the other hand, the manual methods are too slow and cumbersome.